In the case of a known locking or closing device for an ever-ready container for respiration, two container shells of equal size are held together with a single-part narrow tension band completely surrounding the two container shells and equipped with a lock designed as a toggle catch. The single-part tension band is held captive on one of the shells. The toggle-catch-type lock consists of a pivotal hoop at the end of one band, whose external hook-shaped end engages into two hooks at the other end of the band. The tensioned locking hoop, in order to open the container, must be moved about the hoop part which is supported pivotally on one end of the tension band. This is a difficult and uncertain action to be taken by the user of the apparatus in an emergency. Another disadvantage of this opening action is seen in the fact that the single-part narrow tension band surrounding the two container shells causes an unequal distribution of forces, so that an unequal sealing pressure at the circumference of the seal between the two pressed-together container shells cannot be excluded.